Camerapedia

The Konica FS-W SLR is a variant of the FS model. It has an added "timing mechanism" for use in sports and other applications where it would be useful to make a photograph that was imprinted with the exact time. In a sense, this was a precursor of the "date back" offered optionally on many later cameras, that imprinted date and time directly onto the film at the very moment of exposure.